The present invention is generally directed to battery indicating devices and more particularly to a new and improved monitor for monitoring the state of charge of a battery having virtually any type of electrolyte.
In any system wherein one or more storage batteries are utilized it is often desirable, if not essential, to be able to monitor the state of charge of the battery or batteries. In the case of the well known lead-acid type storage battery commonly used in automobiles, it has been found that the most accurate and reliable method of determining the state of battery charge is to measure the specific gravity of the sulfuric acid electrolyte. The specific gravity of the sulfuric acid decreases with decreasing charge therein. As a result, the specific gravity decreases to a point which indicates that the battery requires recharging.
This relationship between electrolyte specific gravity and battery charge has been utilized to advantage in many prior art devices for monitoring charge. For example, U.S. Pat. Nos. 3,597,973 and 3,893,339 which are assigned to the assignee of the present invention fully show and describe such devices. As disclosed therein, the devices include a light transmissive member having an external indicating surface and a reflecting surface adapted to be submerged in the liquid electrolyte. A cage or chamber is connected to the light transmissive member and confines a float member therein having a predetermined density. The light transmissive member is aligned with the chamber and the float member is movable relative to the reflecting surface for indicating the specific gravity of the liquid electrolyte. In one position, the float member is in the bottom of the chamber out of view of the light transmissive member and thus cannot be seen at the external indicating surface. This informs the user that the electrolye specific gravity is below a predetermined value and that recharging is necessary. In another position, a float member is at an upper portion of the chamber aligned with the light transmissive member and is viewable at the external indicating surface. This informs the user that the specific gravity of the electrolyte is above the predetermined value and that the battery's state of charge is such that recharging of the battery is not necessary.
Battery monitors of this type have found wide acceptance for use in batteries having electrolytes in liquid form and which exhibit a change in specific gravity with variations in battery charge. However, new forms of batteries have been developed which do not utilize such a liquid electrolyte but instead utilize an electrolyte or charge transfer medium which is neither liquid nor which exhibits any change in specific gravity with increasing or decreasing battery charge. These batteries include an electrolyte which are either gelular or solid in form. As a result, there is a need in the art for a battery monitor capable of monitoring the state of charge of a battery having an electrolyte which does not vary in specific gravity with variations in battery charge. Furthermore, it would be most preferable for such a monitor to be operable for monitoring the state of charge of batteries having virtually any type of electrolyte.
It is therefore the general object of the present invention to provide a new and improved battery monitor for monitoring the state of charge of a battery.
It is a more particular object of the present invention to provide such a monitor which is capable of monitoring the state of charge of a battery of the type having an electrolyte or charge transfer medium which does not exhibit a change in specific gravity with variations in battery charge.
It is a further object of the present invention to provide such a battery monitor which may be utilized in batteries of the type having a gelular or solid electrolyte.
It is a still further object of the present invention to provide such a battery monitor which may be utilized in conventional lead-acid type batteries as well.